In the field of photomechanical processes, in order to cope with the diversity and complexity of printed matters, there is a need for a photographic material which features excellent producibility of originals and is suitable for use with a stable processing solution, and to simplify the replenishment of processing solutions.
Originals to be used in picture taking contain photocomposed letters, handwritten letters, illustrations, halftoned photographs, etc. Therefore, these originals comprise images having different densities and line widths in admixture. There has therefore been a keen desire for process cameras, photographic materials and image forming method for finishing from these originals with an excellent reproducibility. On the other hand, in plate making of catalogs and large-sized posters, the enlargement or reduction of halftoned photographs is widely required. In plate making with dots enlarged, the number of lines is reduced, blurring the picture. In plate making with dots reduced, the number of lines per unit ink is greater than the original, providing a finer picture. Accordingly, in order to maintain the desired reproducibility of halftone gradation, a method for forming an image with an even wider latitude has been desired.
The light source for process cameras is often a halogen lamp or xenon lamp. In order to obtain an enough sensitivity to an object illuminated with such a light source, the photographic material is normally subjected to orthochromatic sensitization. However, photographic materials which have been orthochromatically sensitized are more affected by the chromatic aberrations of lens and thus are more subject to deterioration of image quality than photographic materials which have not been. This deterioration becomes more remarkable with a xenon lamp.
A system which meets the need for a wide latitude is a method which comprises processing a lithographic silver halide photographic material comprising silver bromochloride (silver chloride content: at least 50% or more) with a hydroquinone developer having an extremely low effective sulfite ion concentration (normally 0.1 mol/liter or less) to provide a line image or halftone image having an image portion and a nonimage portion which are distinctly distinguished from each other, a high contrast and a high blacking density. However, since this method uses a developer with a low sulfite concentration, development is extremely unstable against air oxidation. In order to keep the solution activity constant, various measures must be taken. Further, in this method, the processing speed is extremely low, lowering the working efficiency.
Therefore, an image formation system has been desired which eliminates the instability of image formation due to the above mentioned development method (lithographic development system) by using a processing solution having an excellent preservability to develop a light-sensitive material to provide an ultrahigh contrast photograph. By way of example, a system has been proposed which comprises processing a surface latent image type silver halide photographic material comprising a specific acylhydrazine compound with a developer having an excellent preservability and a pH value of 11.0 to 12.3 and comprising 0.15 mol/liter or more of a sulfite preservative to form an ultrahigh contrast negative image with a .gamma. value of more than 10 as disclosed in U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,272,606, and 4,311,781. This new image formation system is characterized by the fact that it can use silver bromoiodide or silver bromochloroiodide, as opposed to the conventional ultrahigh contrast image formation method which can use only silver bromochloride with a high silver chloride content.
The above mentioned image formation system provides excellent properties, i.e., sharp halftone dot quality, high processing stability, and high reproducibility of the original. In order to cope with the recent diversity of printed matters, a system with an even higher reproducibility of original is desired.
JP-A-61-213847, JP-A-62-260153, JP-A-64-88451, and JP-A-64-72140 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application"), and U.S. Pat. No. 4,684,604 disclose a light-sensitive material comprising a redox compound which undergoes oxidation to release a development inhibitor and perhaps to widen the gradation reproduction range. However, in an ultrahigh contrast processing system using a hydrazine derivative, if such a redox compound is incorporated into a light-sensitive material in an amount sufficient to optimize the reproducibility of line image and halftone image, the development inhibitor which has been released upon development partially flows out. When light-sensitive material comprising such a redox compound is continuously processed in a large amount, the development inhibitor gradually accumulates in the developer. Accordingly, when a developer fatigued from continuous processing is used to develop the light-sensitive material, a higher contrast cannot be provided or the sensitivity is reduced. In particular, when one automatic developing machine is used to develop a light-sensitive material comprising such a redox compound as well as other various light-sensitive materials for picture taking, contact light-sensitive materials and photographic materials, the latter light-sensitive material is adversely affected photographically.
Thus, the amount of such a redox compound to be incorporated into the light-sensitive material is limited. This makes it impossible to provide fully satisfactory results. Further, this process can be used only in a closed system in which a light-sensitive material and a developer are limited to narrow ranges. This system leaves much to be desired.
On the other hand, photographic materials for use in photomechanical processes are sometimes exposed to severe conditions (e.g., high temperature, high humidity) before use. In ultrahigh contrast processing systems using a hydrazine derivative, if a light-sensitive material comprising such a redox compound is exposed to these severe conditions, it can be adversely affected photographically. For example, when such a light-sensitive material is stored at a high temperature or high humidity, it is not only subject to a reduction in the sensitivity but also is prevented from providing a higher contrast, impairing its commercial value.